Under Edit there are three items. They are Surface Type, Set Current Surface, and Implicit Surface.

  1. Surface Type allows a user to specify the surface type that will be used for creating the next surface. This system supports four types of surfaces:

  2. Set Current Surface lets a user to pick a surface to be the current surface. The IDs of all surfaces on the drawing canvas are listed. Thus, selecting a surface ID will make the corresponding surface the current one.

  3. Implicit Surface is designed for processing implicit surfaces. It has the following three sub-items: